Light emitting diode (LED) lighting devices are replacing incandescent lamp lighting devices in many applications including flashlights, automotive tail lamps, buoy lights, etc. LED light sources or lamps offer high efficiency; however, when employed in a lighting device, the efficacy of the lighting device depends upon the beam pattern of the lighting device relative to the requirements for the beam pattern of the emerging light.
The light emitted from an individual LED lamp can have a number of patterns depending upon the construction of the LED lamp. However, it is common for the light to be distributed within a hemisphere about an axis.
It is common for a lighting device to require an emerging light pattern different from the emitted light pattern from the LED lamp and therefore an optic or lens is necessary to redirect the light and modify the emitted light pattern from the LED lamp to match the required emerging light pattern for the lighting device.
In addition to matching the requirement for a particular emerging light pattern from the lighting device in order to maximize the efficacy of the lighting device, the lens should be designed to maximize the percentage of light emitted from the LED lamp which adds to the emerging light pattern from the lighting device.
In addition to having a required emerging light pattern, some lighting devices may also require that they appear evenly illuminating when viewed from outside the lighting device. In order to comply with that requirement, the lens should be designed such that the surface of the lighting device appears evenly illuminating.
Some lighting devices may also have size limitations and need to comply with a requirement that the lens be designed to minimize its size.
Some lighting devices may also require high-intensity emerging light beam patterns requiring a plurality of LEDs. For these devices, the lens must be designed such that a plurality of lenses can be assembled within the size limitations of the lighting device with each lens directing its emitted light into a common beam.
Some lighting devices may also be required to emit a light beam which is elongated beyond an angular beamwidth of eighty degrees.
Some lighting devices may also require a smooth and/or flat exterior surface permitting easy cleaning.